sticky

- mark files for special treatment

Description

The sticky bit (file mode bit 01000, see chmod(2)) is used to
indicate special treatment of certain files and directories. A directory for which
the sticky bit is set restricts deletion of files it contains.
A file in a sticky directory can only be removed or renamed by
a user who has write permission on the directory, and either owns
the file, owns the directory, has write permission on the file, or
is a privileged user. Setting the sticky bit is useful for directories
such as /tmp, which must be publicly writable but should deny users
permission to arbitrarily delete or rename the files of others.

If the sticky bit is set on a regular file and no
execute bits are set, the system's page cache will not be used
to hold the file's data. This bit is normally set on swap
files of diskless clients so that accesses to these files do not
flush more valuable data from the system's cache. Moreover, by default such files
are treated as swap files, whose inode modification times may not necessarily
be correctly recorded on permanent storage.

Any user may create a sticky directory. See chmod for details about
modifying file modes.